Preparation and Properties of Wet-Spun Microcomposite Filaments from Various CNFs and Alginate.

We aimed to improve the mechanical properties of alginate fibers by reinforcing with various cellulose nanofibrils (CNFs). Pure cellulose nanofibril (PCNF), lignocellulose nanofibril (LCNF) obtained via deep eutectic solvent (DES) pretreatment, and TEMPO-oxidized lignocellulose nanofibril (TOLCNF) were employed. Sodium alginate (AL) was mixed with PCNF, LCNF, and TOLCNF with a CNF content of 5-30%. To fabricate microcomposite filaments, the suspensions were wet-spun in calcium chloride (CaCl2) solution through a microfluidic channel. Average diameters of the microcomposite filaments were in the range of 40.2-73.7 µm, which increased with increasing CNF content and spinning rate. The tensile strength and elastic modulus improved as the CNF content increased to 10%, but the addition of 30% CNF deteriorated the tensile properties. The tensile strength and elastic modulus were in the order of LCNF/AL > PCNF/AL > TOLCNF/AL > AL. An increase in the spinning rate improved the tensile properties.

Biologically activatable azobenzene polymers targeted at drug delivery and imaging applications.

Molecular design concepts are described for the preparation of azobenzene polymers capable of showing a tunable response to the rat liver microsome-induced side-chain self-immolation process under hypoxic conditions. It is shown that azobenzene nuclei carrying a donor/acceptor substitution pattern are the most active system towards the enzymatically triggered azobenzene cleavage reaction (half-life = t1/2 = 6 min). Their activity is followed by azobenzene nuclei carrying donor/donor (t1/2 = 20 min), electronically non-substituted (t1/2 = 72 min), and acceptor (t1/2 = 78 min) systems. This trend is preserved when a chemical stimulus, sodium dithionite, replaces the biological reducing conditions and demonstrates generality of the findings, and their potential in proteomics procedures. Furthermore, the established design concepts also permit for variation in polymer structure and topology while still maintaining the electronic substitution pattern. The steric constraints or the inherent character (hydrophilic/hydrophobic) of the azobenzene, however, does not alter the fate of the scission reaction. In all cases, the self-immolation process allows the polymer chain to convert from a chemically neutral to a cationic state. This structural transformation can be used as an activation mechanism (in vitro) to gain entry into cells through electrostatic interactions with the oppositely charged cell membrane and to deliver an anticancer drug. Interestingly, polymer structure now plays a role and bottlebrush-like copolymer show higher selectivity and faster cellular uptake. Finally, the best performing polymer allows for structural modulation into a fluorescent imaging probe. In vivo application to mice suffering from colitis confirms accumulation of the imaging probe in the diseased colon and cecum parts of the body where the endogenous microbial flora is known to produce the activation enzyme. This work, therefore, establishes general principles for the molecular design of biologically activatable and cleavable azobenzene-based polymeric scaffolds applicable to delivery and imaging applications.

Simultaneous Delivery of Electrostatically Complexed Multiple Gene-Targeting siRNAs and an Anticancer Drug for Synergistically Enhanced Treatment of Prostate Cancer.

Simultaneous silencing of multiple apoptosis-related genes is an attractive approach to treat cancer. In this article, we present a multiple gene-targeting siRNA/drug delivery system for prostate cancer treatment with a high efficiency. Bcl-2, survivin, and androgen receptor genes involved in the cell apoptosis pathways were chosen as silencing targets with three different siRNAs. The colloidal nanocomplex delivery system (<10 nm in size) was formulated electrostatically between anionic siRNAs and a cationic drug (BZT), followed by encapsulation with the Pluronic F-68 polymer. The formulated nanocomplex system exhibited sufficient stability against nuclease-induced degradation, leading to successful intracellular delivery for the desired therapeutic performance. Silencing of targeted genes and apoptosis induction were evaluated in vitro on human prostate LNCaP-LN3 cancer cells by using various biological analysis tools (e.g., real-time PCR, MTT cell viability test, and flow cytometry). It was demonstrated that when the total loaded siRNA amounts were kept the same in the nanocomplexes, the simultaneous silencing of triple genes with co-loaded siRNAs (i.e., Bcl-2, survivin, and AR-targeting siRNAs) enhanced BZT-induced apoptosis of cancer cells more efficiently than the silencing of each single gene alone, offering a novel way of improving the efficacy of gene therapeutics including anticancer drug.

An activatable anticancer polymer-drug conjugate based on the self-immolative azobenzene motif.

Triggered cellular uptake of a synthetic graft copolymer carrying an anticancer drug is achieved through self-immolation of the side-chain azobenzene groups. In this concept, the conjugate is initially chemically neutral and does not possess cell-penetrating function. However, upon cleavage of the azobenzene moieties, a cascade process is initiated that ultimately reveals an ammonium cation in the vicinity of the polymer backbone. Hence, self-immolation results in the transformation of the neutral polymer chain into a polycation. This structural transformation allows the conjugate to be taken up by the cancer cells through favorable electrostatic interactions with the negatively charged phospholipid components of the cell membrane. Once inside the cells, the polymer releases covalently attached doxorubicin in a pristine form through a low pH activated release mechanism. The significance of this approach lies in the sensitivity of the azobenzene group to hypoxic conditions and to the enzyme azoreductase that is secreted by the microbial flora of the human colon and suggests a pathway to targeted drug delivery applications under these conditions.